SpaceAPI: more inputs

[CarlFK]

Signals:

• google calendar?
• A hardware toggle? This could be hooked up to anything. For PS:One, it could be the switch that turns the neon OPEN sign on and off.

[eastein]

Discussing with the spaceapi working group, #spaceapi on freenode.

[eastein]

SpaceApi-archive/app-framework#2